Everything You Need to Know About Quality Control in Circuit Manufacturing

October 3, 2023

Nowadays, virtually every kind of electronic device available is powered by one or more printed circuit boards (PCBs). In recent years, these thin sheets of conducting material have become much more advanced and engineered to fit smaller and smaller sizing requirements.

To keep up with such advancements and changes, it is more important than ever for PCB manufacturers to put time and effort into quality control efforts to minimize defects and ensure the calibre of the circuits being implemented in devices far and wide.

Since the reliability of a PCB is crucial for the function of any piece of equipment it is being used in, the quality control measures taken throughout the circuit manufacturing process must be comprehensive.

What are the different quality control tests implemented in circuit manufacturing?

When it comes to circuit manufacturing in Toronto, there are multiple areas where the quality of the circuit could be potentially impacted by even the slightest mishaps, design flaws, or oversights. Therefore, there are several areas where quality control measures must be taken to ensure no issues are present in the final product.

The following are some of the most important tests throughout the quality control process:

1. Visual tests

One type of quality control test that is particularly useful during low-production runs is a visual examination. This test can typically be done by the person who performed the PCB’s assembly. During this visual inspection, it is important that each connection is meticulously checked in a well-lit environment.

2. Microscope tests

Since PCB components are often quite minuscule, inspectors may use handheld optical tools, such as a magnifying glass or a jeweller’s loupe, to avoid straining their eyes during inspections.

However, if they want to get an even closer look, it is possible to do so using a USB microscope to project an up-close image of the PCB’s connections onto a large screen so that they may be closely inspected.

3. In-circuit tests

In-circuit tests encompass two different methods of electronic inspection: a bed of nails inspection and a fixtureless one. A bed of nails test involves the use of a series of small spring-loaded pogo pins that measure resistance by pressing onto various test points. 

On the other hand, fixtureless testing involves sending machine-operated probes across a PCB to check test points at incredibly high speeds.

4. X-ray inspections

With an X-ray, it is possible to perform a non-invasive visual inspection of a PCB. Similar to the USB microscope inspection, you can look closely at various connections on a PCB after receiving an x-ray image of it. Unfortunately, this approach is quite expensive, so it is not used as frequently as others.

5. Saw inspections

A much more invasive inspection method involves slicing through a PCB with a saw. Although this method is destructive to the board, it can make it possible to see the bigger picture of the overall assembly process, so it is occasionally helpful.

6. Automated optical inspections (AOIs)

There are two main types of automated optical inspections. One type, which is often performed with cheaper systems, involves the utilization of inexpensive webcams and Open Source Computer Vision (OpenCV) to compare webcam images of a PCB to images of what has been deemed a perfect board to search for incongruence or defects.

On the other hand, commercial-grade AOI systems use higher-quality cameras and RGB LEDs to reflect light to check the solder quality and search for connection faults.

7. Functional testing

Once a PCB has been manufactured, the functional testing stage involves going through a full trial run to make sure everything is working as it should be. During this test, operators power on the PCB and program it so that it performs a series of self-tests.

8. Camera inspections

Another tool for PCB quality assurance inspections that is highly preferred is an inspection camera, as these cameras make ergonomic viewings of PCB connections possible with the naked eye. 

After high-resolution images are captured, they are pulled up on computer screens and manipulated so that even the tiniest details can be inspected. This also makes it possible to share these images with other departments for further review.

How is quality measured during circuit manufacturing?

There are many different methods to choose from when it comes to testing the quality of a PCB, and some of these approaches may even be used in tandem. Still, how exactly is a PCB’s quality measured at the end of the day? There are a few key quality control metrics that are incredibly important in PCB testing practices. 

One effective quality standard is defects per unit (DPU), which is a measure of the total number of defects found on a given board. The other standard is defects per million opportunities (DPMO), which is a normalizing factor for measuring the total amount of defects on one million boards that are of differing complexities. 

These two metrics allow PCB manufacturers to track both product and process quality. Lead engineers may also want to review board layouts and routing paths to see if improving the circuitry through added layers may be necessary. 

Finally, it is essential to confirm that the nodes and circuits are protected from unwanted noise. You should check that solder masks exist between the pins and the vias and also make sure the board’s silk screening is evident enough.

How Circuits Central Can Help You Manage Circuit Manufacturing Quality Control in Toronto

If you require assistance with circuit manufacturing in Toronto and want to ensure that your PCBs are of the highest quality, Circuits Central can help. We are a world-class electronics manufacturer that offers a full spectrum of PCB manufacturing services, ranging from material procurement to full turnkey manufacturing, PCB assembly, and more. 

We have been helping customers produce some of the most impressive PCBs in the industry for over 25 years, thanks to our knowledge, expertise, advanced equipment, and commitment to quality.

We also offer comprehensive post-production PCB testing that includes x-ray and AOI inspection as well as functional testing, JTAG testing, in-circuit testing, and environmental stress exams, among other methods.

Our team of PCB experts will work with you to develop the best possible testing procedures for your product specifically. In doing so, we will ensure that your PCBs are functioning optimally and free of errors before they leave our facility. 

For more information about how we can help you with circuit manufacturing in Toronto or to learn more about our extensive PCB assembly and manufacturing services, call Circuits Central at 1 (888) 602-7264 or contact us here.

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